Latch structure



March 9,v 1954 R. P. scHERER LATCH STRUCTURE A Filed June 24, 1950 2 Sheets-Sheet l gl ,m

R. P. SCHERER LATCH STRUCTURE March 9, 1954 2 Sheets-Sheet 2 Filed June 24, 1950 Patented Mar. 9,Y 1954 LATCH STRUCTURE Robert Pauli Scherer, Detroit, Mich., assignor to R. P. Scherer Corporation, Detroit, Mich., a corporation of Michigan Application June 24, 1950, Serial No. 170,102

(Cl. 'Z4-2) 8 Claims.

This invention relates to a latch structure particularly designed for a hypo jet injector of the kind shown in my copending application, Serial No. 170,101 led June 24, 1950, but likewise useable wherever a movable element biased to move in one direction is to be latched against such movement.

Several problems presented themselves in the design of a latch structure for a hypo jet injector:

(1) To make an instantaneously releasable support for a heavy load.

(2) To make such a support capable of repeated functioning without undue wear.

(3) To make such a support releasable by a relatively light releasing force which releasing force remains consistent throughout manufacturing variations and over an extended period of use.

(4) To make such a support and releasing means which are compact and capable of being readily reset.

To solve these several problems, research developed the following considerations:

(1) A combination of primary support and secondary support for the heavy load.

(2) A high lever ratio between the primary support and the secondary support.

(3) A primary support off which the load rolls instead of the support being slipped out from under the load.

Therefore a latch roll was adopted having a lever arrangement entirely wit-hin the diameter of the roll which contributes to compactness, and the secondary support adopted was a pivoted latch for the latch roll. The latch has a retrograde camming action on the latch roll to aid in the ease of release, the parts being so arranged that relatching is accomplished by simply restoring the load carrying part to an original position with respect to the primary support, the primary and secondary supports (or latch roll and latch) returning automatically to latched position after which the load can be imposed on the load carrying part and thereby on the primary support.

One object of the present invention therefore is to provide a latch structure which in spite of a heavy load imposed thereon, such as springs or the like tending to move the movable element, is nevertheless readily releasable by light pressure on a release button at the will of the operator.

Another object is to provide a latch structure in which a latch roll constitutes the primary support and coacts with a shoulder of a movable element to hold the movable element against movement due to a bias acting thereon, together with a latch that constitutes the secondary support and releases the latch roll so that it may rotate and thereby release the movable element by a rolling action without breaking down the latching edges which coact between the movable element and the latch roll.

Still. another object is to provide a latch roll so designed in relation to its axis of rotation, and the axis being so related to a shoulder of the movable element, that there is a positive tendency for the latch roll to be rotated to the unlatching position due to the bias which acts on the movable element, thereby making possible the use of a latch of such design that it `may be released by the application of a relatively light force.

A further object is to provide a novel type of latch mechanism for holding springs or other driving means in loaded condition in such a manner that their store of energy may beminfstantaneously and easily released without appreciable wear on the latch mechanism.

A more specific object is to provide a latch structure in the form of a latch roll having a latching shoulder engaged by a latching shoulder of a movable element which is biased to move in one direction, the engagement being to one side of the axis of rotation of the latch roll. A latch for the latch roll is then provided having a surface engagement therewith which is shaped to have a slight tendency to be self-releasing, such self-releasing tendency, however, being of less magnitude than the holding action of the latch-restoring springs so as to reduce the pressure required for release to a predetermined small value.

With these and other objects in View, my invention consists in the construction, arrangement and combination of the various parts of my latch structure, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawings, wherein:

Figure 1 is an enlarged sectional view through a hypo jet injector of the kind shown in my above-mentioned copending application showing the rear half or release button end thereof and illustrating the latch structure of the present invention in association therewith.

Figure 2 is a similar sectional view, this gure being of the ampule containing end of the injector and a continuation of the right hand end of Figure 1, both Figures 1 .and 2 showing the parts in latched position and ready for the latch structure to be released.

Figures 3 and 4 are detail sectional views on the lines 3-3 and 4--4 respectively of Figure l.

Figure 5 is a side elevation of that portion of Figure l adjacent the section lines 3-3 and 4-4 showing the latch housing, a latch in dotted lines, and the end of the latch roll together with portions thereof also dotted.

Figure 6 is a sectional view similar to the left hand end of Figure 1 showing the latch released, the latch roll partially rotated by movement of the movable element, which it normally retains against movement and, by dotted lines, a final position of the latch roll.

Figure 7 is a fragmentary sectional view showing the latch in side elevation and the latch roll in the dotted position of Figure 6 during the latching of the hypo jet injector.

Figure 8 is an enlarged sectional view showing the latch mechanism in a position just prior to being. completely latched; and

-Figure 9 is a still more greatly enlarged sectional view showing the parts in the completely latched position and illustrating constructional features in detail.

First describing the hypo jet injector shown on the accompanying drawings and particularly Figures 1 and 2 in a general way, I have used the reference numeral 20 to indicate a body for most of the mechanism ofthe injector. The body 20 hasl threaded on the forward end thereof a dosage sleeve- 35, and a winding sleeve 48 is rotatable on the rear end thereof as shown in Figures 1 and 2 respectively. The sleeve 13B has an inturned flange 4I coacting with an annular shoulder'ZZ on the body Z6 to prevent longitudinal movement in one direction relative tothe body. A latch housing 55 is screwed into the rear end of the winding sleeve 46 with a thrust bearing assembly 23 interposed between the body and the latch housing.

A release button cap 60 is threaded on the latch housing 5D and the entire assembly of winding sleeve 40, latch housing 5t, and cap 60 is held in the assembled relation by a set screw 42 engaging all three parts and sealed in place, as shown in- Figure 3.

The dosage sleeve 30 has threaded on its forward end an ampule holder l adapted to receive an ampule 'i' IY having medicament 12 there'- in and a cup-like follower 'I3 formed of Neoprene or the like (see Figure 2). The ampule is provided with a reduced discharge nozzle 'i4 perforated by a minute or capillary discharge orifice 15. The ampule holder is covered by resilient nose 'I6 such as one of Neoprene or-the like.

The internal mechanism of the hypo ljet injector includes a primary plunger 80, a secondary plunger 90 which is tubular in character and has a disc-like portion 92, and mechanism for propelling these plungers` and thereby the follower 'I3 forwardly in the ampule 1I to discharge the medicament 'l2 through the orifice l5 thereof as fully explained in my copending application above referred to.

The mechanism mentioned in the preceding paragraph comprises a nut |00, a screw IIB, and a plurality of power springs III. The nut is sleeve-like in character and has a disc-like head I2` provided with spring seats for the springs I I I which springs, at their opposite ends, seat against a partition I I2.of the body 20.

The nut |00 hasthreads |04v at its left end as 4 shown in Figure 1 which cooperate with the threads of the screw IIS. The screw at its left end as shown in Figure l is provided with a head I I5 providing a latching shoulder I I6. The screw head I l5 terminates in a bifurcated portion which results in a pair of spaced blades II'I, the head with its blades being slidable in a square opening 52 of the latch housing 5E]Y (see also Figures 3 and 4) As illustrated in Figure 3, the latch housing is provided with a cross slot 53 in which a secondary support or latch 54 is pivotally mounted. For this purpose a pivot pin 59 is a press fit in the latch and has its ends rotatable in the latch housing. The latch substantially spans the width of the slot 53 and the space between the blades II'I of the screw and is of the shape shown in Figure 1 having a latching shoulder 55 and a spring socket 55. A latch spring 5l has one end seated in the socket andy its other end seated in an opposing socket 58 of the latch housing for tending to rotate the latch counter-clockwise.

Slidably mounted in the release button cap 50 is a release button 6I having a cross bar 62 attached thereto and slidable in the slot 53 of the latch housing 5i) and the space between the blades l il of the screw HD back 0f the latch 54. When this button is depressed, as in Figure 6, it rocks the latch 54 against the bias of the spring 5l as shown.

A primary support or latch roll 63 is provided having end portions 64 and B5 rotatable in the latch housing (see Figure 4), and a latch portion between the end portions which is of the crosssectional shape shown best in Figure 9. This latch portion is of a particular shape having a rst shoulder 6B, a second shoulder 61, and a third shoulder 68, the'purpose of which will hereinafter be described. The shoulders 66 and 61 extend substantially radially of the axis 69 of the latch roll and the shoulder 68 is slightly less than a degree angle to the shoulder B6. The shoulder 6l has a corner cut oi at 61a and the shoulder 66 is rounded at its upper end as shown at 66a. As shown in Figures 1 and 9, the shoulder 61 is adapted to be engaged by the latching shoulder 55 of the latch 54, and the shoulder 66 is adapted to engage the latching shoulder I I5 of thescrew III).

The latch roll 63 (Figures 4 and 5) is biased to rotate counter-clockwise in Figures 1 and 5 to 9 by a latch spring 'l1 wound around a reduced portion 'I8 of the latch roll and having one end received in a hole 3|' thereof as shown by dotted lines in Figure 5 and its other end hooked in a hole 32 ofthe latch housing 50.

rlhe axis of rotation 69 (see Figures 8 and 9) of the latchV roll lies slightly outside line of lower surface of head H5 or slightly beyond the outer limit of the path of travel ofr this surface as shown bythe horizontal and vertical center lines so there is a positive tendency as the springs III' bias the screw Il@ toward the right as indicated by the arrow a. to rotate the latch roll shoulder against the expanding tendency of thepower springs II I, and the shoulder 8G of' the latch roll' rolls out from under the shoulder IIS- of:` the screw IIIl when the latch is operated, thusminimizing the wear between the latch roll and the shoulder II6 as distinguished from an ordinary latch which is pulled from beneath a shoulder with a resulting tendency to break down the edges of the latch and the shoulder. The rounding 66a of the shoulder 66 and the cut-off corner I Ia aid in this respect.

Referring to Figure 9, due to the proximity of the axis 69 to the lower surface of the head H5, the shoulder 66 assumes but a small angle relative to this surface (dotted position) after the screw III) is unlatched and while it isl being moved in a direction opposite the arrow a during the relatching portion of a cycle of operation. This prevents the rounded edge 66a from gouging into the lower surface of the screw during relatching and the rounding 66a is also helpful for this purpose. Also during the relatching an incline II5b of the lower surface of the head M5 permits the latch roll 63 to be gradually rocked by the action of its spring 'I'I back to the position of Figure 8 so the latch 56 can be pivoted by its spring 5l to the latched position.

The latching shoulder 55 of the latch 54 (see Figure 9) is formed on a radius R, the center of which is indicated at 8l. This center is so located relative to the center 82 of oscillation of the latch that the latching shoulder 56 constitutes a camming surface having a slight retrograde movement as obvious by comparing the arcs 83 and 86 formed on a radius R from the center 82 and a radius R from the center 6I. This reduces the pressure required on the release button 6I when it is manually depressed to the position of Figure 6. As an example, the thumb pressure required may be 2 or 3% of the total loading of the springs III or of course may be decreased or increased as desired. Obviously a retrograde camming surface will reduce the pressure required and the greater the oset of the center 8l from the center 82, the greater will be the retrograde movement as the latch is rotated clockwise for releasing the camming shoulder 55 from the latch roll shoulder 6l and vice-versa. While I have described my latch structure particularly designed for a hypo jet injector of the kind disclosed, it is operable in connection with any type of movable element biased in one direction and having a latching shoulder with which the latch roll may engage.

Practical operation In the operation of the hypo jet injector disclosed, assuming the parts to be in the position of Figures 1 and 2, the ampule II is in place and the springs HI are latched in their compressed condition and ready for release. Release is accomplished by depressing the release button 6I to the position shown in Figure 6 so that the latching shoulder 55 of the latch is out of engagement with the second shoulder 6l of the latch roll. The retrograde shape of the shoulder 55 produces a cam action which permits the roll to rotate clockwise slightly as obvious from an inspection of Figure 9 and particularly the arcs 83 and 84 until the corner 61a of the second shoulder 6'! coincides with the upper corner of the latching shoulder 55 whereupon the corner Sla cams the latch out of the way due to the pressure of the power springs I Il tending to move the screw I I6 toward the right as indicated by the arrow a. This tendency is translated to a clockwise tendency for rotation of the latch roll as indicated by the arrow b and that tendency results in rotation, for instance, to the solid line position shown in Figure 6 with the shoulder.

H6 nearly released from the shoulder 66, engaging the rounded edge 66a thereof at that time and nally when the latch roll is rotated to the dotted position of Figures 6 and 9 (the same position as shown solid in Figure 7) the screw H6 will be released and is traveling toward the right as indicated by the arrow cfor actuating the primary and secondary plungers and 90,

the position at that time being shown by dotted` lines in Figure 6. Figure 7 illustrates the final limit of movement of the screw IIO in the discharged condition of the ampule at which time the springs II l are expanded as far as the instrument will permit them to be expanded.

After the injection has been completed, it is necessary to relatch the screw IIU on the latch roll 63 and lock the roll against rotation by the latch 54 before winding the springs III. This is accomplished by rotating the winding sleeve 60 counter-clockwise as far as possible which causes the screw to be screwed backwardly with relation to the nut, the nut remaining in its forward position and the screw finally assuming the position shown in Figure 8, its total movement starting at the position shown in Figure '7. It will be noted that the shoulder II6 of the screw has passed the shoulder 86 of the latch roll which permits the spring -TI of the roll to rotate the roll from the position of Figure 7 to the position of Figure 8 with the right hand edge of the shoulder 66 stopped against the reduced portion of the cocking screw at the bottom of the shoulder l I6. This rotation of the latch roll also permits the spring 5l of the latch 54 to rock it from the position of Figure 7 to the position of Figure 8 behind the shoulder 6'I.

To accomplish the nal latching of the screwl i l 0 (see Figure 1) ,the Winding sleeve 46 is rotated clockwise which will advance the screw back into the nut I Il@ until the shoulder I I6 of the Screw engages the shoulder 66 of the latch roll and rotates the latch roll clockwise from the position of Figure 8 to the position of Figures 1 and 9,v such rot-ation of course being stopped by the shoulder 6l engaging the shoulder 55 as illustrated. At that time the cut-.back incline IIb insures that the shoulder H6 will engage the shoulder 66 to a predetermined distance from the axis 69 to provide the proper leverage necessary to insure rotation of the latch roll 63 under the action of the springs III without any possibility of rotation cf the roll stopping before unl-atching has been completed as might be the case if the cut-back incline were not provided. It will also be noted in Figure 9 that the shoulder 65 in the latched position of the parts is slightly inclined to the left to help in assuring engagement between 66 and H16 a. predetermined distance from the axis E9 for the purpose of keeping the pressure necessary to operate the release button within predetermined limits.

Thereafter further rotation of the winding sleeve 66 produces compression of the power springs II I because the screw II!) is held by the latch roll against forward movement and since the screw is rotating the nut will be retracted along its threads carrying with it the nut head |62 (Figure 2) against the forward ends of the springs, this head of course moving toward the partition H2 (Figure l).

The springs IH can thereafter be compressed as much as desired and the hypo jet injector is.

rendered operable for performing another injection by thumb pressure on the release button 6I.

From the foregoing specification it will-11e.

actuan obvious that' the relatively powerful springs. IH arelatchedA in the; compressed. condition by an eflicientllatchl roll and latch arrangement whichoperates; with a minimum of. Wear so that it is capable of proper operation for. many thousands of'cycles without breakdown of the latchingi edges as.: may occur in many other types of latching devices. When the parts are in the position shown in Figure 9', the shoulders. 65' and l` I'B' are ink contact. at a point sufciently far from the axis. Si) of. thelatch roll 63 that the springs I-IIv areA capable of overcoming all friction involved and rotation of the latch roll is assured; The slightly retrograde camming contour of the shoulder 55 makes the latch easy to release manually in spite of the heavy load of the springs I I l thereon. 'lhe degree of camming may be changed to. get any desired' proportion of release button pressure to power spring pressure.

Some changes may be made in the construction and arrangement of the parts of my latch structure without departing from the real spirit and purpose of my invention, andV it is my intention to cover by my claims any modified forms of structure oruse of mechanical equivalents which may be reasonably included within their scope.

I claim asmy invention:

1. In a latch structure of the character disclosed, a movable element biased tomove inone direction, and means to releasably hold said element y'againstV said movement comprising primary and secondary supports, said primary support being rotatable on an axis adjacent said movable element and having a pair of shoulders, one of said shoulders beingV closer to the axis of rotation than the other, saidv movable element having a shoulder engaging said one of said shoulders, and said secondary support engaging the other of said shoulders and being movable from engagement therewith, said one of said shoulders having a rounded edge over which the shoulder of said movable element rolls as said movable element is released from said primary support.

2. In a latch structure, a movable element biased to move in one direction, and means to releasably hold said element against said movement comprising primary and secondary supports, said primary support comprising a latch roll rotatable on an axis adjacent said movable element and having a pair of shoulders lyingvvithin the circumference of the roll, one of said shoulders being closer to the axis of rotation than the other, said movable element having a shoulder engaging said one of said shoulders, said latch roll being biased to rotate in a direction for engaging said one of said shoulders with said. movable element shoulder and said secondary support comprising a pivoted latch engaging the other of said' shoulders and having a camming action in relation thereto tending to release said pivoted latch from said latch roll.

3. A latch structure for a movable element biased to move in one direction, comprising primary and secondary supports, said primary support being rotatable in bearings adjacent said movable element andv having a pair of shoulders within the bearing circumference, one of said shoulders beingcloser to the axis of rotation than the other, said movable element having a shoulder engaging said closer shoulder of said primary support, and said secondary support being pivoted and engaging the other of said shoulders with a. camming face tending to releasesaid pivoted support from. said: primary support, said closer 8" shoulder having: a rounded` edge over which the shoulder of said movable element rollsfas said movable element is released? from said primary support.

4; In a latch structure, an element biased. to move in one direction, and meansto releasably latch said element against such movement comprising a shoulder on said element at substantially right angles to said direction of movement, a latchz roll rotatably mounted on an axis closely adjacent but beyond the outer boundary of the path of` travel of said shoulder, said latch roll having a shoulder adapted in one position of rotation to engage said shoulder of saidmovabl'e elementV and in another position of rotation to be swung out of the path of said shoulder of said movable element, and a latch having a slightly retrograde cam surface adapted to engage another shoulderv of said latch roll tol pre vent rotation thereof until said latch is released.

5; In a latch structure of the character disclosed, an element biasedto move in one direction, and meansvto releasably latch said element against such movement comprising a shoulder on said element, a latch roll rotatably mounted on anaxis at substantially right angles to said direction of movement, saidy axis being closely adjacent but beyond the outer boundary of the path oftravel of said shoulder, said latch roll having a rounded shoulder adapted in one'position of rotation to engage said shoulder of said movableY element and in another position of rotation to be swung out of the path of said shoulder of said movable element, and a pivoted latch adapted to engage another shoulder of said latch roll to prevent rotation thereof until said pivoted latch is manually released, the portion of said pivoted' latch which engages said latch roll being slightly retrograde cam-shaped:

6L In a latch structure of the character disclosed, a movable element biased to move in one direction, and means to releasably hold said element against such movement comprising a shoulder on said' element, a latchroll rotatably mountedr on an axisv closely adjacent but beyond the outer boundary of the path of movement of said shoulder, said'latch roll having a shoulder withinl the circumference of the roll adapted in one position ofl rotation to engage said shoulder of said movable element and in another position of rotation to be swung clear of the path of said. shoulder of said movable element, and a latch adapted to engage another shoulder of said latch roll within the circumference of the.

roll but farther. from the center of rotationthan said rst shoulder of said latch roll to prevent rotation thereof until said latch is released.

7. In a latch structure, amovable element having a shoulder biased to move along a substantially straight path, a latch roll to prevent such movementl said latch roll' having its axis slightly beyond the outer boundary of the path of move,- ment of said shoulder` along. said' substantially straight path and biased to rotate into said path, said latch roll having a first shoulder substantially radially thereof to engage said movable element shoulder, said. rst shoulder having a rounded edge over which the shoulderV of. saidv movable element. rollsas said movable element. is. releasedr from*4 said first shoulder, saidy latch roll having a-V second shoulder substantially radially thereof, said. first and second shouldersbothbeing Within the-circumference of said latchf roll; a pivoted support having a' oam:surface-operable to normally engage said second shoulder on a line normal to said second shoulder, said cam surface being slightly retrograde with respect to a constant radius from the pivot axis of said support, and a release button engageable with said support to release it from said second shoulder.

8. In a latch structure, a movable element having a shoulder biased to move along a predetermined path, a latch roll to prevent such movement, said latch roll having its axis beyond the outer boundary of the path of movement of said shoulder along said path at a distance less than radius of said latch roll and biased to rotate into said path, said latch roll having a rst shoulder to engage said movable element shoulder, a second shoulder adapted to be engaged by a latch, and a third shoulder to engage one side of said movable element in all positions thereof except when the rst shoulder of the latch roll and the shoulder of the movable element are in supporting relationship, means biasing said latch roll to rotate in a direction to affect such engagement of said third shoulder with said one side of said movable element, and a releasable latch for said second shoulder.

ROBERT PAULI SCHERER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,187,135 Derby June 13, 1916 2,337,361 Vienneau Dec. 21, 1943 2,476,022 Bennett July 12, 1949 FOREIGN PATENTS Number Country Date 615,797 Great Britain Jan. 12, 1949 

